Solve for $x$ and $y$ using substitution. ${6x-y = -9}$ ${x = -3y+8}$
Explanation: Since $x$ has already been solved for, substitute $-3y+8$ for $x$ in the first equation. ${6}{(-3y+8)}{- y = -9}$ Simplify and solve for $y$ $-18y+48 - y = -9$ $-19y+48 = -9$ $-19y+48{-48} = -9{-48}$ $-19y = -57$ $\dfrac{-19y}{{-19}} = \dfrac{-57}{{-19}}$ ${y = 3}$ Now that you know ${y = 3}$ , plug it back into $\thinspace {x = -3y+8}\thinspace$ to find $x$ ${x = -3}{(3)}{ + 8}$ $x = -9 + 8$ ${x = -1}$ You can also plug ${y = 3}$ into $\thinspace {6x-y = -9}\thinspace$ and get the same answer for $x$ : ${6x - }{(3)}{= -9}$ ${x = -1}$